In a saucepan, combine raspberries and water. Crush gently, bring to a simmer for 2 minutes, strain, and return juice to the saucepan. Stir in sugar and lemon juice, simmer until reduced. Cool completely.

Using a stand mixer, beat the heavy cream on medium-high speed until stiff peaks form, about 3-4 minutes. Transfer to a separate bowl.

In the same mixer bowl, combine mascarpone cheese, sugar, raspberry syrup, and vanilla. Beat until smooth. Fold in half of the whipped cream.

Dip each ladyfinger in the chilled raspberry syrup quickly and arrange in the bottom of an 8-inch dish. Spread half of the mascarpone filling over them and sprinkle with half of the grated white chocolate.

Repeat the layering process with the remaining ladyfingers, mascarpone filling, and grated white chocolate on top.

Cover and refrigerate for at least 6 hours or overnight before serving for optimal flavor and texture.